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<body>
  <script>
    class Parent {
      constructor(value){
        this.value = value;
      }
      getValue(){
        console.log(this.value);
      }
    }
    class Child extends Parent{
      constructor(value){
        super(value)
        this.value = value;
      }
    }
    let child = new Child(1);
    child.getValue();
    console.log(child instanceof Parent);
    
    
  </script>
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